The Spinopelvic Alignment in Patients with Prior Knee or Hip Arthroplasty Undergoing Elective Lumbar Surgery.

BACKGROUND CONTEXT: Concurrent degeneration of the lumbar spine, hip, and knee can cause significant disability and lower quality of life. Osteoarthritis in the lower extremities can lead to movement limitations, possibly requiring total knee arthroplasty (TKA) or total hip arthroplasty (THA). These procedures often impact spinal posture, causing alterations in spinopelvic alignment and lumbar spine degeneration. It is unclear if patients with a history of prior total joint arthroplasty (TJA) have different spinopelvic alignment compared to patients without. PURPOSE: To assess the relationship between a history of previous THA or TKA, as well as combined THA and TKA, and the spinopelvic alignment in patients undergoing elective lumbar surgery for degenerative conditions. STUDY DESIGN: A retrospective analysis was conducted on patients who underwent lumbar surgery for degenerative conditions. The patients were stratified based on a history of TKA, THA, or both TKA and THA. PATIENT SAMPLE: A total of 632 patients (63% female) with an average age of 64 ± 11 years and an average BMI of 30 ± 6 kg/m2 were included. OUTCOME MEASURES: Patients were stratified based on a history of THA, TKA, or combined THA and TKA. Spinopelvic parameters (lumbar lordosis (LL), sacral slope (SS), pelvic tilt (PT), and pelvic incidence (PI)) were assessed. The relationship between spinopelvic alignment and prior TKA, THA or TKA and THA was analyzed METHODS: The data was tested for normal distribution using the Shapiro-Wilk test. We analyzed the relationship between the spinopelvic parameters and the different arthroplasty groups. Differences in scores between groups were examined using ANOVA. Tukey's Honestly Significant Difference test was used for pairwise comparison for significant ANOVA test results. Multivariable linear regression was applied, adjusted for age, sex and BMI. RESULTS: A total of 632 patients (63% female) were included in the study. Of these patients, 74 (12%) had a history of isolated TKA, 40 (6%) had prior isolated THA, and 15 (2%) had TKA and THA prior to lumbar surgery. Patients with prior arthroplasty were predominantly female (59%) and significantly older (68 ± 7 years vs. 63 ± 12 years, p<0.001) with a significantly higher BMI (31 ± 6 kg/m2 vs. 29 ± 6 kg/m2, p<0.001). The LL was significantly lower (45.0° ± 13 vs. 50.9° ± 14 p=0.011) in the arthroplasty group compared to the non-arthroplasty group. A history of isolated TKA was significantly associated with lower LL (Est= -3.8, 95% CI -7.3 to -0.3, p=0.031) and SS (Est= -2.6, 95% CI -5.0 to -0.2, p=0.012) compared to patients without TJA. Prior combined THA and TKA was found to be significantly associated with a higher PT compared to the non-arthroplasty group (Est= 5.1, 95% CI 0.4-9.8, p=0.034). CONCLUSION: The spinopelvic alignment differs between patients with and without prior TJA who undergo elective lumbar surgery. The study shows that a history of TKA is significantly associated with a lower LL and SS. The combination of THA and TKA was associated with a significantly higher PT. These findings highlight the complex relationship between the hip, spine, and knee. Moreover, the results could aid in enhancing preoperative planning of lumbar surgery in patients with known TJA.

The Disaggregation of the Oswestry Disability Index in Patients undergoing Lumbar Surgery for Degenerative Lumbar Spondylolisthesis.

BACKGROUND CONTEXT: The Oswestry Disability Index (ODI), is a widely used patient-reported outcome measure (PROM) for assessing functional status in individuals with lumbar spine pathology. The ODI is used by surgeons to determine the initial status and monitor progress after surgery. Compiled ODI data enables comparisons between different surgical techniques. Degenerative lumbar spondylolisthesis (DLS) often causes symptoms such as back pain and neurogenic claudication affecting quality of life and activities of daily living captured by the ODI. Despite extensive studies on ODI changes after spinal surgery, little is known about the characteristics and changes in the different ODI subsections. PURPOSE: To analyze the baseline characteristics and changes in total ODI and ODI subsections 2 years after elective lumbar surgery. STUDY DESIGN: Retrospective analysis on patients prospectively enrolled who underwent spinal surgery for degenerative lumbar spondylolisthesis from 2016 to 2018. The ODI was assessed preoperatively and 2 years postoperatively. PATIENT SAMPLE: A total of 265 patients were included in the study, 60% were female. The mean age of the patients was 67 ± 8 years, and the mean BMI was 30 ± 6 kg/m2. OUTCOME MEASURES: The analysis considered the differences in ODI scores before and after surgery, as well as the changes in all ODI subsections 2 years after elective lumbar surgery for DLS. METHODS: The analysis evaluated differences in ODI scores and variations in different subsections. Patients without an ODI follow-up at 2 years were excluded from the study. The study utilized the Wilcoxon Signed Rank Test for all pre-post paired samples. The Wilcoxon rank sum test was used for sex and procedure comparisons for overall ODI and ODI subsection analysis. Univariate linear regression was applied for overall and subsection specific ODI outcomes with age and BMI as independent variables, respectively. The statistical significance level was set at p<0.05. RESULTS: Improvement in ODI was observed in 242 patients (91%). The highest baseline disability values were found for the questions regarding pain intensity (3.4 ± 1.3), lifting (3.2 ± 1.9), and standing (3.4 ± 1.3). The lowest preoperative functional limitations were observed in sleeping (1.6 ± 1.3), personal care (1.6 ± 1.4), traveling (1.6 ± 1.2) and sitting (1.5 ± 1.4). At the 2-year follow-up, there was significant improvement in all questions and the overall ODI (all p<0.001). The ODI subsections that showed the greatest absolute improvements were changing degree of pain (-2.6), with 89% of patients experiencing improvement, standing (-2.4) with 87% of patients experiencing improvement, and pain intensity (-2.1) with 81% of patients experiencing improvement. The subsections with the least improvement were personal care (-0.6), sitting (-0.7), and sleeping (-0.9). The study found that female patients had a significantly higher preoperative disability in various subsections but showed greater improvement in total ODI compared to male patients (p=0.001). Additionally, improvement in sitting (p<0.001), traveling (p<0.001), social life (p<0.001) and sleeping (p=0.018) were significantly higher in female patients. Older patients showed significantly less improvement in sitting (p=0.005) and sleeping (p=0.002). A higher BMI was significantly associated with less improvement in changing degree of pain (p=0.025) and higher baseline disability in various subsections. Patients who underwent decompression and fusion had significantly higher baseline disability in several subsections compared to those who underwent decompression alone. There was no significant difference between decompression alone and decompression with fusion in terms of overall improvement in the ODI and improvement in the subsections. CONCLUSION: These results offer a more comprehensive understanding of ODI and its changes across different subsections. This insight is invaluable for improving preoperative education and effectively managing patient expectations regarding potential post-surgery disability in specific areas.

The Association between prior arthroplasty and Paraspinal Muscle Degeneration in patients undergoing elective lumbar surgery.

PURPOSE: Spinal and lower extremity degeneration often causes pain and disability. Lower extremity osteoarthritis, eventually leading to total knee- (TKA) and -hip arthroplasty (THA), can alter posture through compensatory mechanisms, potentially causing spinal misalignment and paraspinal muscle (PM) atrophy. This study aims to evaluate the association between prior THA or TKA and PM-degeneration in patients undergoing elective lumbar surgery for degenerative conditions. METHODS: A retrospective analysis of patients undergoing lumbar surgery for degenerative conditions was conducted. Patients were categorized based on prior THA, TKA, or both. Quantitative analysis of functional cross-sectional area (fCSA) and fat infiltration (FI) of psoas, multifidus (MF), and erector spinae (ES) muscles at L4-level was performed using T2-weighted MRI images. The association between the FI and fCSA of the PM and prior arthroplasty was investigated. Differences were assessed using ANOVA and multivariable linear regression. RESULTS: Overall, 584 patients (60% female, 64 ± 12 years) were included. 66 patients (11%) had prior TKA, 36 patients (6%) THA, and 15 patients (3%) both TKA and THA. Patients with arthroplasty were mostly female (57%) and notably older (p < 0.001). The FI of the MF and the ES was significantly higher in the arthroplasty-group (both p < 0.001). Patients with prior TKA showed significantly higher FI (Est = 4.3%, p = 0.013) and lower fCSA (Est=-0.9 cm2, p = 0.012) in the MF compared to the non-arthroplasty-group. CONCLUSION: This study demonstrates a significant lower fCSA and higher FI in the MF among individuals with prior TKA. This highlights the complex knee-spine relationship and how these structures interact with each other.

Relationship between Lumbar Foraminal Stenosis and Multifidus Muscle Atrophy - A Retrospective Cross-Sectional Study.

STUDY DESIGN: Retrospective cross-sectional study. OBJECTIVE: To evaluate the relationship between lumbar foraminal stenosis (LFS) and multifidus muscle atrophy. BACKGROUND: The multifidus muscle is an important stabilizer of the lumbar spine. In LFS, the compression of the segmental nerve can give rise to radicular symptoms and back pain. LFS can impede function and induce atrophy of the segmentally innervated multifidus muscle. METHODS: Patients with degenerative lumbar spinal conditions who underwent posterior spinal fusion for degenerative lumbar disease from December 2014 to February 2024 were analyzed. Multifidus fatty infiltration (FI) and functional cross-sectional area (fCSA) were determined at the L4 upper endplate axial level on T2- weighted MRI scans using dedicated software. Severity of LFS was assessed at all lumbar levels and sides using the Lee classification (Grade: 0 - 3). For each level, Pfirrmann and Weishaupt gradings were used to assess intervertebral disc disease (IVDD) and facet joint osteoarthritis (FJOA), respectively. Multivariable linear mixed models were run for the LFS grade of each level and side separately as the independent predictor of multifidus FI and fCSA. Each analysis was adjusted for age, sex, BMI, as well as FJOA and IVDD of the level corresponding to the LFS. RESULTS: A total of 216 patients (50.5% female) with a median age of 61.6 years (IQR=52.0 - 69.0) and a median BMI of 28.1 kg/m2 (IQR=24.8 - 33.0) were included. Linear mixed model analysis revealed that higher multifidus FI (Estimate [Confidence interval]=1.7% [0.1 - 3.3], P=0.043) and lower fCSA (-18.6 mm2 [-34.3 - -2.6], P=0.022) were both significantly predicted by L2-L3 level LFS severity. CONCLUSION: The observed positive correlation between upper segment LFS and multifidus muscle atrophy points towards compromised innervation. This necessitates further research to establish the causal relationship and guide prevention efforts.

Importance of the lumbar paraspinal muscles on the maintenance of global sagittal alignment after lumbar pedicle subtraction osteotomy.

OBJECTIVE: There are limited data about the influence of the lumbar paraspinal muscles on the maintenance of sagittal alignment after pedicle subtraction osteotomy (PSO) and the risk factors for sagittal realignment failure. The authors aimed to investigate the influence of preoperative lumbar paraspinal muscle quality on the postoperative maintenance of sagittal alignment after lumbar PSO. METHODS: Patients who underwent lumbar PSO with preoperative lumbar MRI and pre- and postoperative whole-spine radiography in the standing position were included. Spinopelvic measurements included pelvic incidence, sacral slope, pelvic tilt, L1-S1 lordosis, T4-12 thoracic kyphosis, spinosacral angle, C7-S1 sagittal vertical axis (SVA), T1 pelvic angle, and mismatch between pelvic incidence and L1-S1 lordosis. Validated custom software was used to calculate the percent fat infiltration (FI) of the psoas major, as well as the erector spinae and multifidus (MF). A multivariable linear mixed model was applied to further examine the association between MF FI and the postoperative progression of SVA over time, accounting for repeated measures over time that were adjusted for age, sex, BMI, and length of follow-up. RESULTS: Seventy-seven patients were recruited. The authors' results demonstrated significant correlations between MF FI and the maintenance of corrected sagittal alignment after PSO. After adjustment for the aforementioned parameters, the model showed that the MF FI was significantly associated with the postoperative progression of positive SVA over time. A 1% increase from the preoperatively assessed total MF FI was correlated with an increase of 0.92 mm in SVA postoperatively (95% CI 0.42-1.41, p < 0.0001). CONCLUSIONS: This study included a large patient cohort with midterm follow-up after PSO and emphasized the importance of the lumbar paraspinal muscles in the maintenance of sagittal alignment correction. Surgeons should assess the quality of the MF preoperatively in patients undergoing PSO to identify patients with severe FI, as they may be at higher risk for sagittal decompensation.

Relationship between facet joint osteoarthritis and lumbar paraspinal muscle atrophy: a cross-sectional study.

OBJECTIVE: The paraspinal muscles play an essential role in the stabilization of the lumbar spine. Lumbar paraspinal muscle atrophy has been linked to chronic back pain and degenerative processes within the spinal motion segment. However, the relationship between the different paraspinal muscle groups and facet joint osteoarthritis (FJOA) has not been fully explored. METHODS: In this cross-sectional study, the authors analyzed adult patients who underwent lumbar spinal surgery between December 2014 and March 2023 for degenerative spinal conditions and had preoperative MRI and CT scans. The fatty infiltration (FI) and functional cross-sectional area (fCSA) of the psoas, erector spinae, and multifidus muscles were assessed on axial T2-weighted MR images at the level of the upper endplate of L4 based on established studies and calculated using custom-made software. Intervertebral disc degeneration at each lumbar level was evaluated using the Pfirrmann grading system. The grades from each level were summed to report the cumulative lumbar Pfirrmann grade. Weishaupt classification (0-3) was used to assess FJOA at all lumbar levels (L1 to S1) on preoperative CT scans. The total lumbar FJOA score was determined by adding the Weishaupt grades of both sides at all 5 levels. Correlation and linear regression analyses were conducted to assess the relationship between FJOA and paraspinal muscle parameters. RESULTS: A total of 225 patients (49.7% female) with a median age of 61 (IQR 54-70) years and a median BMI of 28.3 (IQR 25.1-33.1) kg/m2 were included. After adjustment for age, sex, BMI, and the cumulative lumbar Pfirrmann grade, only multifidus muscle fCSA (estimate -4.69, 95% CI -6.91 to -2.46; p < 0.001) and FI (estimate 0.64, 95% CI 0.33-0.94; p < 0.001) were independently predicted by the total FJOA score. A similar relation was seen with individual Weishaupt grades of each lumbar level after controlling for age, sex, BMI, and the Pfirrmann grade of the corresponding level. CONCLUSIONS: Atrophy of the multifidus muscle is significantly associated with FJOA in the lumbar spine. The absence of such correlation for the erector spinae and psoas muscles highlights the unique link between multifidus muscle quality and the degeneration of the spinal motion segment. Further research is necessary to establish the causal link and the clinical implications of these findings.

Association between skin ultrasound parameters and revision surgery after posterior spinal fusion.

PURPOSE: The literature is scarce in exploring the role of imaging parameters like ultrasound (US) as a biomarker for surgical outcomes. The purpose of this study is to investigate the associations between skin US parameters and revision surgery following spine lumbar fusion. METHODS: Posterior lumbar fusion patients with 2-years follow-up were assessed. Previous fusion or revision not due to adjacent segment disease (ASD) were excluded. Revisions were classified as cases and non-revision were classified as controls. US measurements conducted at two standardized locations on the lumbar back. Skin echogenicity of the average dermal (AD), upper 1/3 of the dermal (UD), lower 1/3 of the dermal (LD), and subcutaneous layer were measured. Echogenicity was calculated with the embedded echogenicity function of our institution's imaging platform (PACS). Statistical significance was set at p < 0.05. RESULTS: A total of 128 patients (51% female, age 62 [54-72] years) were included in the final analysis. 17 patients required revision surgery. AD, UD, and LD echogenicity showed significantly higher results among revision cases 124.5 [IQR = 115.75,131.63], 128.5 [IQR = 125,131.63] and 125.5 [IQR = 107.91,136.50] compared to the control group 114.3 [IQR = 98.83,124.8], 118.5 [IQR = 109.28,127.50], 114 [IQR = 94.20,126.75] respectively. CONCLUSION: The findings of this study demonstrate a significant association between higher echogenicity values in different layers of the dermis and requiring revision surgery. The results provide insights into the potential use of skin US parameters as predictors for revision surgery. These findings may reflect underlying alterations in collagen. Further research is warranted to elucidate the mechanisms driving these associations.

What is the Association of the Subsections of the Oswestry Disability Index and Overall Improvement Two Years after Lumbar Surgery for Degenerative Lumbar Spondylolisthesis?

STUDY DESIGN: Retrospective review of a prospective cohort study. OBJECTIVE: To identify the association between Oswestry Disability Index (ODI) subsections and overall improvement 2 years after lumbar surgery for degenerative lumbar spondylolisthesis (DLS). BACKGROUND: DLS often necessitates lumbar surgery. The ODI is a trusted measure for patient-reported outcomes (PROMs) in assessing spinal disorder outcomes. Surgeons utilize the ODI for baseline functional assessment and post-surgery progress tracking. However, it remains uncertain if and how each subsection influences overall ODI improvement. METHODS: This retrospective cohort study analyzed patients who underwent lumbar surgery for DLS between 2016 and 2018. Preoperative and 2-year postoperative ODI assessments were conducted. The study analyzed postoperative subsection scores and defined ODI improvement as ODIpreop-ODIpostop >0. Univariate linear regression was applied, and receiver operating characteristic (ROC) analysis determined cut-offs for subsection changes and postoperative target values to achieve overall ODI improvement. RESULTS: 265 patients (60% female, mean age 67±8 y) with a baseline ODI of 50±6 and a postoperative ODI of 20±7 were included. ODI improvement was noted in 91% (242 patients). Achieving a postoperative target score of ≤2 in subsections correlated with overall ODI improvement. Walking had the highest predictive value for overall ODI improvement (AUC 0.91, sensitivity 79%, specificity 91%). Pain intensity (AUC 0.90, sensitivity 86%, specificity 83%) and changing degree of pain (AUC 0.87, sensitivity 86%, specificity 74%) were also highly predictive. Sleeping had the lowest predictability (AUC 0.79, sensitivity 84%, specificity 65%). Except for sleeping, all subsections had a Youden-index >50%. CONCLUSION: These findings demonstrate how the different ODI subsections associate with overall improvement post-lumbar surgery for DLS. This understanding is crucial for refining preoperative education, addressing particular disabilities, and evaluating surgical efficacy. Additionally, it shows that surgical treatment does not affect all subsections equally.

Importance of the cervical paraspinal muscles in postoperative patient-reported outcomes and maintenance of sagittal alignment after anterior cervical discectomy and fusion.

OBJECTIVE: The aim of this study was to investigate the influence of preoperatively assessed paraspinal muscle parameters on postoperative patient-reported outcomes and maintenance of cervical sagittal alignment after anterior cervical discectomy and fusion (ACDF). METHODS: Patients with preoperative and postoperative standing cervical spine lateral radiographs and preoperative cervical MRI who underwent an ACDF between 2015 and 2018 were reviewed. Muscles from C3 to C7 were segmented into 4 functional groups: anterior, posteromedial, posterolateral, and sternocleidomastoid. The functional cross-sectional area and also the percent fat infiltration (FI) were calculated for all groups. Radiographic alignment parameters collected preoperatively and postoperatively included C2-7 lordosis and C2-7 sagittal vertical axis (SVA). Neck Disability Index (NDI) scores were recorded preoperatively and at 2 and 4-6 months postoperatively. To investigate the relationship between muscle parameters and postoperative changes in sagittal alignment, multivariable linear mixed models were used. Multivariable linear regression models were used to analyze the correlations between the changes in NDI scores and the muscles' FI. RESULTS: A total of 168 patients with NDI and 157 patients with sagittal alignment measurements with a median follow-up of 364 days were reviewed. The mixed models showed that a greater functional cross-sectional area of the posterolateral muscle group at each subaxial level and less FI at C4-6 were significantly associated with less progression of C2-7 SVA over time. Moreover, there was a significant correlation between greater FI of the posteromedial muscle group measured at the C7 level and less NDI improvement at 4-6 months after ACDF. CONCLUSIONS: The findings highlight the importance of preoperative assessment of the cervical paraspinal muscle morphology as a predictor for patient-reported outcomes and maintenance of C2-7 SVA after ACDF.

Abdominal Aortic Calcification is Associated with Degeneration of The Paraspinal Muscles - A Retrospective cross-sectional Study.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To analyze the relationship of abdominal aortic calcification (AAC) and a reduction in the cross-sectional area (CSA) and the fatty infiltration (FI) of the paravertebral muscles in patients undergoing lumbar fusion surgery. BACKGROUND: Both AAC and paraspinal muscle degeneration have been shown to be associated with poorer outcomes after surgical treatment of degenerative diseases of the lumbar spine. However, there is a lack of data on the association between AAC and paraspinal muscle changes in patients undergoing spine surgery. METHODS: We retrospectively analyzed patients undergoing lumbar fusion for degenerative spinal pathologies. Muscular and spinal degeneration were measured on magnetic resonance imaging (MRI). AAC was classified on lateral lumbar radiographs. The association of AAC and paraspinal muscle composition was assessed by a multivariate regression analysis adjusted for age, sex, body mass index (BMI), comorbidities, and lumbar degeneration. RESULTS: A total of 301 patients was included. Patients with AAC showed significantly higher degrees of intervertebral disc and facet joint degeneration as well as higher total endplate scores at the L3/4 level. The univariable regression analysis showed a significant positive correlation between the degree of AAC and the FI of the erector spinae (b=0.530, P<0.001) and multifidus (b=0.730, P<0.001). The multivariable regression analysis showed a significant positive correlation between the degree of AAC and the FI of the erector spinae (b=0.270, P=0.006) and a significant negative correlation between the degree of AAC and the CSA of the psoas muscle (b=-0.260, P=0.003). CONCLUSION: This study demonstrates a significant and independent association between AAC and degeneration of the erector spinae and the psoas muscles in patients undergoing lumbar fusion. As both AAC and degeneration of paraspinal muscles impact postoperative outcomes negatively, preoperative assessment of AAC may aid in identifying patients at higher risk after lumbar surgery.

How much improvement in Oswestry Disability Index is Necessary to make your Patient Satisfied after Lumbar Surgery?

STUDY DESIGN: Retrospective review of cohort studies. OBJECTIVE: To clarify the necessary ODI improvement for patient satisfaction two years after lumbar surgery. BACKGROUND: Evaluating elective lumbar surgery care often involves patient-reported outcomes (PRO). While postoperative functional improvement measured by ODI is theoretically linked to satisfaction, conflicting evidence exists regarding this association. METHODS: Baseline ODI and 2-year postoperative ODI were assessed. Patient satisfaction, measured on a scale from 1 to 5, with scores ≥4 considered satisfactory, was evaluated. Patients with incomplete follow-up were excluded. Statistical analyses included Mann-Whitney-U and multivariable logistic regression adjusted for age, sex, and BMI. Receiver operating characteristic (ROC) analysis determined threshold values for ODI improvement and postoperative target ODI indicative of patient satisfaction. RESULTS: 383 patients were included (mean age 65±10 y, 57% female). ODI improvement was observed in 91% of patients, with 77% reporting satisfaction scores ≥4. Baseline ODI (median 62, IQR 46-74) improved to a median of 10 (IQR 1-10) 2 years postoperatively. Baseline (OR 0.98, P=0.015) and postoperative ODI scores (OR 0.93, P<0.001), as well as the difference between them (OR 1.04, P< 0.001), were significantly associated with patient satisfaction. Improvement of ≥38 ODI points or a relative change of ≥66% was indicative for patient satisfaction, with higher sensitivity (80%) and specificity (82%) for the relative change versus the absolute change (69%, 68%). With a sensitivity of 85% and a specificity of 77%, a postoperative target ODI of ≤24 indicated patient satisfaction. CONCLUSION: Lower baseline ODI and greater improvements in postoperative ODI are associated with an increased likelihood of patient satisfaction. A relative improvement of ≥66% or achieving a postoperative ODI score of ≤24 were the most indicative thresholds for predicting patient satisfaction, proving more sensitivity and specificity than an absolute change of ≥38 points.

Association Between Severity of Cervical Central Spinal Stenosis and Paraspinal Muscle Parameters in Patients Undergoing Anterior Cervical Discectomy and Fusion.

STUDY DESIGN: Retrospective study. OBJECTIVE: The aim of this study was to evaluate the association between severity and level of cervical central stenosis (CCS) and the fat infiltration (FI) of the cervical multifidus/rotatores (MR) at each subaxial levels. SUMMARY OF BACKGROUND DATA: The relationship between cervical musculature morphology and the severity of CCS is poorly understood. METHODS: Patients with preoperative cervical magnetic resonance imaging (MRI) who underwent anterior cervical discectomy and fusion (ACDF) were reviewed. The cervical MR were segmented from C3 to C7 and the percent FI was measured using a custom-written Matlab software. The severity of the CCS at each subaxial level was assessed using a previously published classification. Grade 3, representing a loss of cerebrospinal fluid space and deformation of the spinal cord > 25%, was set as the reference and compared to the other gradings. Multivariable linear regression analyses were conducted and adjusted for age, sex, and body mass index. RESULTS: 156 consecutive patients were recruited. A spinal cord compression at a certain level was significantly associated with a greater FI of the MR below that level. After adjustment for the above-mentioned confounders, our results showed that spinal cord compression at C3/4 and C4/5 was significantly associated with greater FI of the MR from C3 to C6 and C5 to C7, respectively. A spinal cord compression at C5/6 or C6/7 was significantly associated with greater FI of the MR at C7. CONCLUSION: Our results demonstrated significant correlations between the severity of CCS and a greater FI of the MR. Moreover, significant level-specific correlations were found. A significant increase in FI of the MR at the levels below the stenosis was observed in patients presenting with spinal cord compression. Given the segmental innervation of the MR, the increased FI might be attributed to neurogenic atrophy. LEVEL OF EVIDENCE: 3.

Asymmetrical atrophy of the paraspinal muscles in patients undergoing unilateral lumbar medial branch radiofrequency neurotomy.

ABSTRACT: Lumbar medial branch radiofrequency neurotomy (RFN), a common treatment for chronic low back pain due to facet joint osteoarthritis (FJOA), may amplify paraspinal muscle atrophy due to denervation. This study aimed to investigate the asymmetry of paraspinal muscle morphology change in patients undergoing unilateral lumbar medial branch RFN. Data from patients who underwent RFN between March 2016 and October 2021 were retrospectively analyzed. Lumbar foramina stenosis (LFS), FJOA, and fatty infiltration (FI) functional cross-sectional area (fCSA) of the paraspinal muscles were assessed on preinterventional and minimum 2-year postinterventional MRI. Wilcoxon signed-rank tests compared measurements between sides. A total of 51 levels of 24 patients were included in the analysis, with 102 sides compared. Baseline MRI measurements did not differ significantly between the RFN side and the contralateral side. The RFN side had a higher increase in multifidus FI (+4.2% [0.3-7.8] vs +2.0% [-2.2 to 6.2], P = 0.005) and a higher decrease in multifidus fCSA (-60.9 mm 2 [-116.0 to 10.8] vs -19.6 mm 2 [-80.3 to 44.8], P = 0.003) compared with the contralateral side. The change in erector spinae FI and fCSA did not differ between sides. The RFN side had a higher increase in multifidus muscle atrophy compared with the contralateral side. The absence of significant preinterventional degenerative asymmetry and the specificity of the effect to the multifidus muscle suggest a link to RFN. These findings highlight the importance of considering the long-term effects of lumbar medial branch RFN on paraspinal muscle health.

Assessing paraspinal muscle atrophy with electrical impedance myography: Limitations and insights.

Paraspinal muscle atrophy is gaining attention in spine surgery due to its link to back pain, spinal degeneration and worse postoperative outcomes. Electrical impedance myography (EIM) is a noninvasive diagnostic tool for muscle quality assessment, primarily utilized for patients with neuromuscular diseases. However, EIM's accuracy for paraspinal muscle assessment remains understudied. In this study, we investigated the correlation between EIM readings and MRI-derived muscle parameters, as well as the influence of dermal and subcutaneous parameters on these readings. We retrospectively analyzed patients with lumbar spinal degeneration who underwent paraspinal EIM assessment between May 2023 to July 2023. Paraspinal muscle fatty infiltration (FI) and functional cross-sectional area (fCSA), as well as the subcutaneous thickness were assessed on MRI scans. Skin ultrasound imaging was assessed for dermal thickness and the echogenicities of the dermal and subcutaneous layers. All measurements were performed on the bilaterally. The correlation between EIM readings were compared with ultrasound and MRI parameters using Spearman's correlation analyses. A total of 20 patients (65.0% female) with a median age of 69.5 years (IQR, 61.3-73.8) were analyzed. The fCSA and FI did not significantly correlate with the EIM readings, regardless of frequency. All EIM readings across frequencies correlated with subcutaneous thickness, echogenicity, or dermal thickness. With the current methodology, paraspinal EIM is not a valid alternative to MRI assessment of muscle quality, as it is strongly influenced by the dermal and subcutaneous layers. Further studies are required for refining the methodology and confirming our results.

The relationship between paraspinal muscle atrophy and degenerative lumbar spondylolisthesis at the L4/5 level.

BACKGROUND/CONTEXT: Degenerative lumbar spondylolisthesis (DLS) is a prevalent spinal condition that can result in significant disability. DLS is thought to result from a combination of disc and facet joint degeneration, as well as various biological, biomechanical, and behavioral factors. One hypothesis is the progressive degeneration of segmental stabilizers, notably the paraspinal muscles, contributes to a vicious cycle of increasing slippage. PURPOSE: To examine the correlation between paraspinal muscle status on MRI and severity of slippage in patients with symptomatic DLS. STUDY DESIGN/SETTING: Retrospective cross-sectional study at an academic tertiary care center. PATIENT SAMPLE: Patients who underwent surgery for DLS at the L4/5 level between 2016-2018 were included. Those with multilevel DLS or insufficient imaging were excluded. OUTCOME MEASURES: The percentage of relative slippage (RS) at the L4/5 level evaluated on standing lateral radiographs. Muscle morphology measurements including functional cross-sectional area (fCSA), body height normalized functional cross-sectional area (HI) of Psoas, erector spinae (ES) and multifidus muscle (MF) and fatty infiltration (FI) of ES and MF were measured on axial MR. Disc degeneration and facet joint arthritis were classified according to Pfirrmann and Weishaupt, respectively. METHODS: Descriptive and comparative statistics, univariable and multivariable linear regression models were utilized to examine the associations between RS and muscle parameters, adjusting for confounders sex, age, BMI, segmental degeneration, and back pain severity and symptom duration. RESULTS: The study analyzed 138 out of 183 patients screened for eligibility. The median age of all patients was 69.5 years (IQR 62 to 73), average BMI was 29.1 (SD±5.1) and average preoperative ODI was 46.4 (SD±16.3). Patients with Meyerding-Grade 2 (M2, N=25) exhibited higher Pfirrmann scores, lower MFfCSA and MFHI, and lower BMI, but significantly more fatty infiltration in the MF and ES muscles compared to those with Meyerding Grade 1 (M1). Univariable linear regression showed that each cm2 decrease in MFfCSA was associated with a 0.9%-point increase in RS (95% CI -1.4 to - 0.4, p<.001), and each cm2/m2 decrease in MFHI was associated with an increase in slippage by 2.2%-points (95% CI -3.7 to -0.7, p=.004). Each 1%-point rise in ESFI and MFFI corresponded to 0.17%- (95% CI 0.05-0.3, p=.01) and 0.20%-point (95% CI 0.1-0.3 p<.001) increases in relative slippage, respectively. Notably, after adjusting for confounders, each cm2 increase in PsoasfCSA and cm2/m2 in PsoasHI was associated with an increase in relative slippage by 0.3% (95% CI 0.1-0.6, p=.004) and 1.1%-points (95% CI 0.4-1.7, p=.001). While MFfCSA tended to be negatively associated with slippage, this did not reach statistical significance (p=.105). However, each 1%-point increase in MFFI and ESFI corresponded to increases of 0.15% points (95% CI 0.05-0.24, p=.002) and 0.14% points (95% CI 0.01-0.27, p=.03) in relative slippage, respectively. CONCLUSION: This study found a significant association between paraspinal muscle status and severity of slippage in DLS. Whereas higher degeneration of the ES and MF correlate with a higher degree of slippage, the opposite was found for the psoas. These findings suggest that progressive muscular imbalance between posterior and anterior paraspinal muscles could contribute to the progression of slippage in DLS.

Abdominal aortic calcification is an independent predictor of perioperative blood loss in posterior spinal fusion surgery.

OBJECTIVE: Abdominal aortic calcification (AAC), often found incidentally on lateral lumbar radiographs, is increasingly recognized for its association with adverse outcomes in spine surgery. As a marker of advanced atherosclerosis affecting cardiovascular dynamics, this study evaluates AAC's impact on perioperative blood loss in posterior spinal fusion (PSF). METHODS: Patients undergoing PSF from March 2016 to July 2023 were included. Estimated blood loss (EBL) and total blood volume (TBV) were calculated. AAC was assessed on lateral lumbar radiographs according to the Kauppila classification. Predictors of the EBL-to-TBV ratio (%EBL/TBV) were examined via univariable and multivariable regression analyses, which adjusted for parameters such as hypertension and aspirin use. RESULTS: A total of 199 patients (47.2% female) were analyzed. AAC was present in 106 patients (53.3%). AAC independently predicted %EBL/TBV, accounting for an increase in blood loss of 4.46% of TBV (95% CI 1.17-7.74, p = 0.008). CONCLUSIONS: This is the first study to identify AAC as an independent predictor of perioperative blood loss in PSF. In addition to its link to degenerative spinal conditions and adverse postoperative outcomes, the relationship between AAC and increased blood loss warrants attention in patients undergoing PSF.

Spine-specific sarcopenia: distinguishing paraspinal muscle atrophy from generalized sarcopenia.

BACKGROUND CONTEXT: Atrophy of the paraspinal musculature (PM) as well as generalized sarcopenia are increasingly reported as important parameters for clinical outcomes in the field of spine surgery. Despite growing awareness and potential similarities between both conditions, the relationship between "generalized" and "spine-specific" sarcopenia is unclear. PURPOSE: To investigate the association between generalized and spine-specific sarcopenia. STUDY DESIGN: Retrospective cross-sectional study. PATIENT SAMPLE: Patients undergoing lumbar spinal fusion surgery for degenerative spinal pathologies. OUTCOME MEASURES: Generalized sarcopenia was evaluated with the short physical performance battery (SPPB), grip strength, and the psoas index, while spine-specific sarcopenia was evaluated by measuring fatty infiltration (FI) of the PM. METHODS: We used custom software written in MATLAB® to calculate the FI of the PM. The correlation between FI of the PM and assessments of generalized sarcopenia was calculated using Spearman's rank correlation coefficient (rho). The strength of the correlation was evaluated according to established cut-offs: negligible: 0-0.3, low: 0.3-0.5, moderate: 0.5-0.7, high: 0.7-0.9, and very high≥0.9. In a Receiver Operating Characteristics (ROC) analysis, the Area Under the Curve (AUC) of sarcopenia assessments to predict severe multifidus atrophy (FI≥50%) was calculated. In a secondary analysis, factors associated with severe multifidus atrophy in nonsarcopenic patients were analyzed. RESULTS: A total of 125 (43% female) patients, with a median age of 63 (IQR 55-73) were included. The most common surgical indication was lumbar spinal stenosis (79.5%). The median FI of the multifidus was 45.5% (IQR 35.6-55.2). Grip strength demonstrated the highest correlation with FI of the multifidus and erector spinae (rho=-0.43 and -0.32, p<.001); the other correlations were significant (p<.05) but lower in strength. In the AUC analysis, the AUC was 0.61 for the SPPB, 0.71 for grip strength, and 0.72 for the psoas index. The latter two were worse in female patients, with an AUC of 0.48 and 0.49. Facet joint arthropathy (OR: 1.26, 95% CI: 1.11-1.47, p=.001) and foraminal stenosis (OR: 1.54, 95% CI: 1.10-2.23, p=.015) were independently associated with severe multifidus atrophy in our secondary analysis. CONCLUSION: Our study demonstrates a low correlation between generalized and spine-specific sarcopenia. These findings highlight the risk of misdiagnosis when relying on screening tools for general sarcopenia and suggest that general and spine-specific sarcopenia may have distinct etiologies.

Association between lumbar intervertebral vacuum phenomenon severity and posterior paraspinal muscle atrophy in patients undergoing spine surgery.

PURPOSE: Intervertebral vacuum phenomenon (IVP) and paraspinal muscular atrophy are age-related changes in the lumbar spine. The relationship between both parameters has not been investigated. We aimed to analyze the correlation between IVP and paraspinal muscular atrophy in addition to describing the lumbar vacuum severity (LVS) scale, a new parameter to estimate lumbar degeneration. METHODS: We analyzed patients undergoing spine surgery between 2014 and 2016. IVP severity was assessed utilizing CT scans. The combination of vacuum severity on each lumbar level was used to define the LVS scale, which was classified into mild, moderate and severe. MRIs were used to evaluate paraspinal muscular fatty infiltration of the multifidus and erector spinae. The association of fatty infiltration with the severity of IVP at each lumbar level was assessed with a univariable and multivariable ordinal regression model. RESULTS: Two hundred and sixty-seven patients were included in our study (128 females and 139 males) with a mean age of 62.6 years (55.1-71.2). Multivariate analysis adjusted for age, BMI and sex showed positive correlations between LVS-scale severity and fatty infiltration in the multifidus and erector spinae, whereas no correlation was observed in the psoas muscle. CONCLUSION: IVP severity is positively correlated with paraspinal muscular fatty infiltration. This correlation was stronger for the multifidus than the erector spinae. No correlations were observed in the psoas muscle. The lumbar vacuum severity scale was significantly correlated with advanced disc degeneration with vacuum phenomenon.

Decision-making Algorithm for the Surgical Treatment of Degenerative Lumbar Spondylolisthesis of L4/L5.

STUDY DESIGN: A retrospective analysis of prospectively collected data. OBJECTIVE: To report the decision-making process for decompression alone (DA) and decompression and fusion (DF) at a tertiary orthopedic center and compare the operative outcomes between both groups. BACKGROUND: Controversy exists around the optimal operative treatment for DLS, either with DF or DA. Although previous studies tried to establish specific indications, clinical decision-making algorithms are needed. MATERIALS AND METHODS: Patients undergoing spinal surgery for DLS at L4/5 were retrospectively analyzed. A survey of spine surgeons was performed to identify factors influencing surgical decision-making, and their association with the surgical procedure was tested in the clinical data set. We then developed a clinical score based on the statistical analysis and survey results. The predictive capability of the score was tested in the clinical data set with a receiver operating characteristic (ROC) analysis. To evaluate the clinical outcome, two years follow-up postoperative Oswestry Disability Index (ODI), postoperative low back pain (LBP) (Numeric Analog Scale), and patient satisfaction were compared between the DF and DA groups. RESULTS: A total of 124 patients were included in the analysis; 66 received DF (53.2%) and 58 DA (46.8%). Both groups showed no significant differences in postoperative ODI, LBP, or satisfaction. The degree of spondylolisthesis, facet joint diastasis and effusion, sagittal disbalance, and severity of LBP were identified as the most important factors for deciding on DA or DF. The area under the curve of the decision-making score was 0.84. At a cutoff of three points indicating DF, the accuracy was 80.6%. CONCLUSIONS: The two-year follow-up data showed that both groups showed similar improvement in ODI after both procedures, validating the respective decision. The developed score shows excellent predictive capabilities for the decision processes of different spine surgeons at a single tertiary center and highlights relevant clinical and radiographic parameters. Further studies are needed to assess the external applicability of these findings.

Relationship between lumbar spinal stenosis and axial muscle wasting.

BACKGROUND CONTEXT: Although the effect of lumbar spinal stenosis (LSS) on the lower extremities is well documented, limited research exists on the effect of spinal stenosis on the posterior paraspinal musculature (PPM). Similar to neurogenic claudication, moderate to severe spinal canal compression can also interfere with the innervation of the PPM, which may result in atrophy and increased fatty infiltration (FI). PURPOSE: This study aims to assess the association between LSS and atrophy of the PPM. STUDY DESIGN: Retrospective cross-sectional study. PATIENT SAMPLE: Patients undergoing MRI scans at a tertiary orthopedic center for low back pain or as part of a preoperative evaluation. OUTCOME MEASURES: The functional cross-sectional area (fCSA) and percent fatty infiltration (FI) of the PPM at L4. METHODS: Lumbar MRIs of patients at a tertiary orthopedic center indicated due to lower back pain (LBP) or as a presurgical workup were analyzed. Patients with previous spinal fusion surgery or scoliosis were excluded. LSS was assessed according to the Schizas classification at all lumbar levels. The cross-sectional area of the PPM was measured on a T2-weighted MRI sequence at the upper endplate of L4. The fCSA and fatty infiltration (FI) were calculated using custom software. Crude differences in FI and fCSA between patients with no stenosis and at least mild stenosis were tested with the Wilcoxon signed-rank test. To account for possible confounders, a multivariable linear regression model was used to adjust for age, sex, body mass index (BMI), and disc degeneration. A subgroup analysis according to MRI indication was performed. RESULTS: A total of 522 (55.7% female) patients were included. The median age was 61 years (IQR: 51-71). The greatest degree of moderate and severe stenosis was found at L4/5, 15.7%, and 9.2%, respectively. Stenosis was the least severe at L5/S1 and was found to be 2% for moderate and 0.2% for severe stenosis. The Wilcoxon test showed significantly increased FI of the PPM with stenosis at any lumbar level (p<.001), although no significant decrease in fCSA was observed. The multivariable regression model showed a significant increase in FI with increased LSS at L1/2, L2/3, and L3/4 (p=.013, p<.01 and p=.003). The severity of LSS at L4/5 showed a positive association with the fCSA (p=.019). The subgroup analysis showed, the effect of LSS was more pronounced in nonsurgical patients than in patients undergoing surgery. CONCLUSIONS: In this study, we demonstrated a significant and independent association between LSS and the composition of the PPM, which was dependent on the level of LSS relative to the PPM. In addition to neurogenic claudication, patients with LSS might be especially susceptible to axial muscle wasting, which could worsen LSS due to increased spinal instability, leading to a positive feedback loop.